One of Beijing's major new subway lines has almost hit its expected passenger numbers for the year 2032, says a new report on the city's traffic.

Around 800,000 journeys were made each day on Subway Line 5, which opened in 2007 and runs 27 km on a north-south route through the Chinese capital, says the report by the Beijing Municipal Committee of the Chinese People's Political Consultative Conference.

The figure, which planners anticipated reaching in another 22 years, was cited in the report as an example of the challenges facing the city's transport authorities.

Meanwhile, the surging growth in private car ownership has resulted in worsening road congestion in urban Beijing, with the total peak traffic periods rising from three and a half hours a day in 2008 to five hours.

The city had more than 3.29 million private cars as of February, each running 15,000 km a year on average -- double the average mileage of Tokyo motorists, said the report.

Mao Baohua, a transport expert with Beijing Jiaotong University, said the basic solution was to adjust traffic structure and encourage people to take public transport.

However, Mao said public transport was not an attractive option as it usually took longer than driving one's own car as a result of the time spent waiting and the distances from homes and destinations to bus stops.

Since March, Beijing has been encouraging "green" transport, which includes bicycles and public buses, in a bid to ease traffic and cut travel times for commuters.

Beijing's resident population was 17.55 million in 2009.